[Firebase-storage][Android] Error: An unknown error occurred, please check the HTTP result code and inner exception for server response.

Error: An unknown error occurred, please check the HTTP result code and inner exception for server response.

const file = File.fromPath(files.files[0], true);

gives me

"_path": "/storage/emulated/0/Download/877981_QSG_SSB600-SOUNDBAR_ml.pdf",
"_name": "877981_QSG_SSB600-SOUNDBAR_ml.pdf",
"_extension": ".pdf"

Upload

firebase()
.storage()
.ref()
.child(remoteFullPath)  // Firebase url
.putFile(localFullPath) // /storage/emulated/0/Download/877981_QSG_SSB600-SOUNDBAR_ml.pdf
.on('state_changed', {
    complete() {
        console.info('uploadFile', 'completed');
    },
    error(err) {
        console.error('uploadFile', 'error', err);
    },
    next(snapshot) {
        console.info('uploadFile', 'next', 'state', snapshot.state);
        if (snapshot.totalBytes) {
            console.log('uploadFile', 'next', 'progress %', snapshot.bytesTransferred / snapshot.totalBytes ?? 0 * 100);
        }
        if (snapshot.error) {
            console.error('uploadFile', 'next', snapshot.error);
        }
    },
});

Any ideas?

The reported entry points are File.fromPath and Firebase Storage ref().child().putFile() on Android; first reproduce the PDF upload using the shown local path and inspect the HTTP result code and inner exception. Done means identifying a reproducible cause and confirming the upload succeeds, but the issue names no source file or test.